A beautifully eclectic mix of architectural styles.

A preserved oak tree about 3,500 years old found in Riga, Latvia.

This ancient Irish tower could easily have stood in for Rapunzel's prison.

Perfectly preserved ancient monastery in an impossibly dramatic location on a rocky island in the Atlantic.

Originally envisioned by King Ludwig II to rival Versailles, Herrenchiemsee's "New Palace" remains half-gilded for lack of funds.

The fairy tale castle of the "fairy-tale king."

What looks like a normal building is really a hollow facade hiding a subway vent.

The industrial architecture honors the laborers who brought the Exposition Universelle of 1900 to life.

Former hunting lodge of a duke who was an avid collector of impressionist works.

The spiral staircase hidden inside this giant Parisian column was likely built for Catherine de Medici's astrologer.

Beggars were miraculously "cured" of their fake ailments when they returned home to this 17th century Paris slum each night.

Original cabaret handbills, posters, and feline artwork are a purrfect highlight of the Museum of Montmartre.

Known as the "Dodo Manège," this carousel features a herd of animals that have disappeared—or may be gone soon.

Medieval museum built over Roman baths that features famous tapestries of a lady and a unicorn.

This statue was given to France by the United States to commemorate the centennial of the French Revolution.

An "inside out" building in the historical center of Paris, featuring Europe’s largest modern art museum.

Abandoned railway line circling the city of Paris.

His "Lionheart" is entombed separately from the rest of his body.

This medieval tower is all that remains of the castle where Joan of Arc was held before being burned at the stake.

An ancient ossuary in Rouen.

The tallest outdoor elevator in Europe rockets passengers on a dizzyingly precarious ride to the top of a mountain.

These spooky and unusual stone formations create an underworldly landscape.

A king's bloodstained shirt is among the gruesome collection of artifacts displayed below Stockholm's Royal Palace.

It was meant to help transport wounded soldiers to a secret underground hospital.